From owner-freebsd-smp Fri Oct 24 10:16:39 1997 Return-Path: Received: (from root@localhost) by hub.freebsd.org (8.8.7/8.8.7) id KAA04871 for smp-outgoing; Fri, 24 Oct 1997 10:16:39 -0700 (PDT) (envelope-from owner-freebsd-smp) Received: from deimos.nc.com (deimos.nc.com [207.88.167.190]) by hub.freebsd.org (8.8.7/8.8.7) with ESMTP id KAA04861; Fri, 24 Oct 1997 10:16:36 -0700 (PDT) (envelope-from TYANG@nc.com) Received: (from oracle@localhost) by deimos.nc.com (8.8.4/8.8.4) id KAA12913; Fri, 24 Oct 1997 10:14:08 -0700 (PDT) Message-Id: <199710241714.KAA12913@deimos.nc.com> Date: 24 Oct 97 10:13:27 -0700 From: "Tina Yang" To: shieyuan@eecs.harvard.edu, owner-freebsd-smp@freebsd.org Subject: Re: SMP is slower when two processors are enabled Cc: freebsd-smp@freebsd.org MIME-Version: 1.0 X-Mailer: Oracle InterOffice (version 4.1.1.1.10) Content-Type: multipart/mixed; boundary="=_ORCL_2577328_0_1191971024111509_0" Sender: owner-freebsd-smp@freebsd.org X-Loop: FreeBSD.org Precedence: bulk --=_ORCL_2577328_0_1191971024111509_0 Content-Transfer-Encoding:quoted-printable Content-Type:text/plain; charset="iso-8859-1" >ShieYuan Wang said: >> protocol stack to transfer unlimited data on the same local host. If I >> only enable one processor, the throughput can be 35 MB/sec. However if >> I enable the other processor hoping to get better throughput, I only get >> 12 MB/sec. >> >> I know that locking overhead between multiple processors may be a lot. But >> I never thought that it could be so high. Could anyone give me some clues >> ABOUT THIS BAD Performance? My SMP 3.0 was installed about 6 months ago. >> Does the more recent SMP have better performance and have solved the >> performance problem? Your suggestion will be highly appriciated. >> >Most likely it is the overhead of moving data between CPUs. Could be >cache effects also. > >-- >John Interesting. Is it true that SMP 3.0 kernel is still single-threaded ? Since stcp/rtcp is io intensive, it's like you still only have one thread of execution most of the time (like UP), and in the mean time, you lost the UP cache efficiency as well when two processors alternately execute the kernel ?? - Tina --=_ORCL_2577328_0_1191971024111509_0 Content-Type:message/rfc822 Date: 23 Oct 97 17:14:48 From:"John S. Dyson " To:shieyuan@eecs.harvard.edu,(ShieYuan,Wang) Subject:Re: SMP is slower when two processors are enabled Cc:freebsd-smp@FreeBSD.ORG Return-Path: Received:from maildrop.nc.com (proxy@nc.com [207.88.167.98]) by deimos.nc.com (8.8.4/8.8.4) with SMTP id RAA23966 for ; Thu, 23 Oct 1997 17:50:15 -0700 (PDT) Received:(from proxy@localhost) by maildrop.nc.com (8.6.12/8.6.9) id RAA17164 for ; Thu, 23 Oct 1997 17:48:43 -0700 Received:from sarip.sol.net(169.207.30.120) by sebastian.nc.com via smap (V2.0) id xma017160; Thu, 23 Oct 97 17:48:17 -0700 Received:from hub.freebsd.org (hub.FreeBSD.ORG [204.216.27.18]) by sarip.sol.net (8.8.7/8.8.4) with ESMTP id TAA06466; Thu, 23 Oct 1997 19:36:29 -0500 (CDT) Received:(from root@localhost) by hub.freebsd.org (8.8.7/8.8.7) id RAA08117 for smp-outgoing; Thu, 23 Oct 1997 17:15:01 -0700 (PDT) (envelope-from owner-freebsd-smp) Received:from dyson.iquest.net (dyson.iquest.net [198.70.144.127]) by hub.freebsd.org (8.8.7/8.8.7) with ESMTP id RAA08096 for ; Thu, 23 Oct 1997 17:14:56 -0700 (PDT) (envelope-from toor@dyson.ique Received:(from root@localhost) by dyson.iquest.net (8.8.7/8.8.5) id TAA01451; Thu, 23 Oct 1997 19:14:48 -0500 (EST) Message-Id:<199710240014.TAA01451@dyson.iquest.net> In-Reply-To:<199710232354.TAA27809@steward.eecs.harvard.edu> from ShieYuan Wang at "Oct 23, 97 07:54:21 pm" Sender:owner-freebsd-smp@FreeBSD.ORG X-Loop:FreeBSD.org Precedence: bulk MIME-Version: 1.0 Content-Type:text/plain; charset=US-ASCII Content-Transfer-Encoding:7bit ShieYuan Wang said: > protocol stack to transfer unlimited data on the same local host. If I > only enable one processor, the throughput can be 35 MB/sec. However if > I enable the other processor hoping to get better throughput, I only get > 12 MB/sec. > > I know that locking overhead between multiple processors may be a lot. But > I never thought that it could be so high. Could anyone give me some clues > about this bad performance? My SMP 3.0 was installed about 6 months ago. > Does the more recent SMP have better performance and have solved the > performance problem? Your suggestion will be highly appriciated. > Most likely it is the overhead of moving data between CPUs. Could be cache effects also. -- John dyson@freebsd.org jdyson@nc.com --=_ORCL_2577328_0_1191971024111509_0--